in this article six new copoly(amide-imide)s (11a-c) were synthesized through the directpolycondensation reaction of 1,3-bis[4,4'-(trimellitimido) phenoxy] propane (6) with 3,3'-diamino diphenyl sulfone (7), 4,4'-diaminodiphenyl ether (8) and 1,5-naphtalene (9) in thepresence of fumaric acid (10) as a second diacid in a medium consisting of n-methyl-2-pyrrolidone, triphenyl phosp...
